Description of the Prior Art
Squeegee rollers for use in photographic apparatus, such as instant cameras, are well known. The EK-6 Instant Camera, for example, manufactured by the Eastman Kodak Company, Rochester, N.Y., is adapted to expose and initiate processing of so-called instant film units of the integral type. These film units each include a pod containing processing fluid. The pod is adapted to be ruptured, subsequent to a photographic exposure, upon introduction of the film unit into the squeegee rollers. As the film unit is driven through the nip of the squeegee rollers, the processing fluid is distributed within the film unit as a layer over image-forming areas of the film unit to initiate the processing of the photographic image. In order to distribute a uniform layer of the fluid processing composition within the film unit, it is well known to provide the rollers with various contours other than that of a right-regular cylinder. For example, in U.S. Pat. No. 4,319,827, there is shown an instant camera wherein one of the squeegee rollers is contoured with a crown configuration. To manufacture this roller according to the aforementioned patent, it is first necessary to machine a stainless steel roller to the crown shape. Thereafter, the roller is roughened or textured to increase its frictional characteristics by subjecting the roller to an electrical discharge machining (EDM) operation. This latter operation forms minute craters in the surface of the roller. In the process of forming these craters, the surface of the roller is subjected to bombardment by very high energy ions which cause surface and subsurface material on the roller to be displaced into an annular ridge that circumscribes each crater. This patent also teaches that the roughened surface of the roller can be adjusted so as to effect minor changes in fluid thickness control. In the EDM process, the operation contemplates the use of rapid pulsing of the EDM source while the roller is rotated and the source moved axially relative to the roller. The pulsing of the source for the treating of any one roller contemplates the use of a specific pulse on time period and employs a specific pulse current during such period. Minor differences in spread characteristics of one roller pair relative to another roller pair may be provided by treating the one roller pair such that they are subjected to a higher or lower pulse on time or alternatively a higher or lower pulse current.
One disadvantage with this method of manufacture is the extra expense required to machine rollers to form a crown or other complex contour prior to texturing the roller. It is therefore an object of the invention to provide an improved method and apparatus for manufacturing a textured roller having an effective complex contour without the need for machining the roller with a complex contour prior to the step of adding a texture to the surface thereof.